Jan. 23, 2012 -- Some kids with
autism will no longer qualify for that diagnosis as they grow older.

Now a new study shows that whether or not a child "outgrows" their autism may be related to the number and severity of other physical and psychological problems that are part of their original diagnosis.

The study is published in the journal Pediatrics. It compared more than 1,300 children with a past or current diagnosis of autism. About one-third of the kids in the survey had once been diagnosed with autism but were no longer considered to have the condition.

"The main study objective is to try to see what co-existing conditions, if any, would help us to distinguish people who grow out of the autism diagnosis," says researcher Li-Ching Lee, PhD, ScM, a research scientist at the Johns Hopkins Bloomberg School of Public Health, in Baltimore, Md.

In addition to autism, researchers asked parents if their children had ever been diagnosed with other problems, including attention-deficit hyperactivity disorder (ADHD), a learning disability, developmental delay, speech or hearing problems, anxiety, depression, behavioral or conduct problems, and seizures or epilepsy.

Researchers adjusted their results to account for the influences of other things that are known to affect autism and development, including race and gender, the family's income and education level, health insurance coverage, or whether the children were enrolled in a personalized education plan at school.

Conditions That Complicate Autism

Among preschoolers, kids who were diagnosed with a current diagnosis of autism were almost five times more likely to have two or more other conditions than those kids who had a previous diagnosis of autism. Learning disabilities and developmental delays were the most significant predictors of having a current autism diagnosis in 3- to 5-year-olds.

Among 6- to 11-year-olds, kids with a current autism diagnosis were significantly more likely than kids with a past diagnosis to have once had a speech problem or to be currently experiencing moderate to severe anxiety.

Among teens, kids with a current autism diagnosis were significantly more likely to also have a speech problem or mild epilepsy than kids with a past autism diagnosis.

Having a past hearing problem, on the other hand, made it significantly more likely that a child or teen would no longer be diagnosed with autism.

The symptoms of hearing impairment in young children can mimic symptoms of autism. In some cases, when the hearing problems are addressed, the behavioral and developmental problems also resolve.

Experts who were not involved in the research say it's important for a couple of reasons.

Treatment May Help Kids With Co-Occurring Conditions

"It illustrates, again, the fact that there are some common co-occurring disorders that do occur in young individuals with autism and they're relatively frequent. And this is another way of getting some insight into how frequent they are," says Joseph Horrigan, MD, head of medical research for the New York City-based nonprofit Autism Speaks.

He says many of the co-occurring conditions, like ADHD, can be effectively treated with medications or cognitive behavioral therapy. And treatment may relieve some of the distress and dysfunction that many people with autism and their families face.

The second reason the study is noteworthy, Horrigan says, is that it sheds some light on the differences between those kids diagnosed with autism who will see their symptoms improve and those who don't.

He cautions, however, that because the research is just a snapshot in time, it can't say very much about why some people's symptoms become milder over time while others continue to qualify for an autism diagnosis.

"It doesn't really get into that notion of how does the pattern change for an individual, or what sort of things might have happened that may have been associated with a change," like medication, or early, intensive behavioral therapy, he says.

For that, he says, a longer study that follows patients over time will be needed.